JPS62236135A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the wear resistance, durability, and traveling stability of the titled medium by using specified two kinds of lubricants which are hardly compatible with each other to form an insular lubricating coated film on the surface of a magnetic layer. CONSTITUTION:At least two kinds of lubricants shown by formulas (I) and (II) are applied on the surface of the magnetic layer. Since both lubricants are hardly compatible with each other and never mixed with each other, phase separation is caused microscopically, one lubricant having higher affinity for the surface of the magnetic layer due to its characteristic and molecular structure is continuously coated on the surface of the magnetic layer to form 'the sea', and the other lubricant having lower affinity is discontinuously coated to form 'the islands' which are dispersed and retained in the other lubricating coated film. Consequently, an insular lubricating film is formed on the surface of the magnetic layer. In the formulas, X and Y are a fluorine atom, a hydrophilic group, or a monovalent group having a carbon-carbon double bond at the molecular terminal, (l), (m), and (n) are an integer, (l) is 10-100, (m) is 5-100, and (n) is 10-200.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to magnetic recording media such as magnetic tapes, magnetic disks, and magnetic cards.

[Conventional technology]

A magnetic recording medium, in which a magnetic layer consisting of a thin film of metal or metal oxide alone with high coercive force is provided on a non-magnetic support, has an extremely flat magnetic layer surface and a high coefficient of friction, so it is difficult to connect with the magnetic head or guide part. It is susceptible to wear and damage due to sliding contact. For this reason, conventionally, a lubricating film made of various polymers such as higher fatty acids or their metal salts or plasma polymers of organosilicon threads has been deposited on the surface of the magnetic layer, thereby reducing the coefficient of friction on the surface of the magnetic layer. Efforts have been made to reduce this and improve wear resistance, durability, and running stability.

In addition, even in magnetic recording media that have a magnetic layer formed by applying and drying a magnetic paint, it is required to significantly improve the wear resistance of the magnetic layer along with smoothing the surface of the magnetic layer, which is desirable for electromagnetic conversion characteristics. be done. Therefore, conventional techniques have been used to coat the surface of the magnetic layer with a lubricating film similar to the one described above, or to impregnate the magnetic layer with various lubricants and allow it to ooze out onto the surface of the magnetic layer. Efforts are being made to improve wear resistance.

[Problem that the invention seeks to solve]

However, in the conventional method of depositing a lubricating film described above, if the surface of the magnetic layer and the magnetic head or guide portion with which it comes into sliding contact are both ultra-smooth, the lubrication effect cannot be achieved under conditions where they slide against each other at high speed. If the lubricant does not perform to its full potential, the viscous resistance of the lubricant itself increases, resulting in poor running stability.
There was a problem that the output fluctuation became large. In addition, there have been cases where sticking occurs at the contact portion between the guide portion and the magnetic layer, causing the magnetic tape to stop.

Therefore, the present invention prevents the viscous resistance of the lubricant from increasing even under the above-mentioned high-speed sliding conditions by forming a lubricating film with a specific structure that has never been tried before on the surface of the magnetic layer. The object of the present invention is to obtain a magnetic recording medium that does not cause sticking at the guide portion and that satisfies the abrasion resistance, durability, and running stability of the magnetic layer.

[Means for solving problems]

In order to achieve the above object, the present invention uses a combination of at least two types of lubricants that are difficult to dissolve in each other as lubricants, thereby forming a sea-island pattern on the surface of a magnetic layer formed on a non-magnetic support. It is designed to form a lubricating film.

That is, when at least two types of lubricants mentioned above are applied to the surface of the magnetic layer, they do not mix with each other because they are difficult to mix, and exhibit a micro phase separation phenomenon, and due to their properties and molecular structures, One lubricant, which has a stronger affinity for the other, forms a continuous film on the surface of the magnetic layer, forming a “sea”.
Therefore, the other lubricant having a weaker affinity does not form a continuous film as described above, but becomes an island dispersed in the one lubricant film, which forms a sea-island lubricant film. It will be formed on the surface of the magnetic layer.

The above-mentioned sea-island-shaped lubricating film can be used even under conditions where the magnetic layer and the magnetic head or guide portion slide at high speed through this film, even if the original sea-island structure is destroyed by the sliding. A new sea-island structure appears due to a similar microphase separation phenomenon, so that a stable film state is always maintained.

Therefore, even under the high-speed sliding conditions as described above, the increase in viscous resistance as in the conventional case is no longer observed. Moreover, such a sea-island-shaped lubricating film exhibits strong film properties with durability or durability, so it exhibits a much better lubricating effect than the aforementioned "sea" lubricating film alone. By avoiding an increase in viscous resistance, running stability is improved, output fluctuations are reduced, and the sticking phenomenon between the guide portion and the magnetic layer is suppressed.

As described above, in the present invention, by forming an island-like lubricating film on the surface of the magnetic layer by using a combination of at least two types of lubricants that are hardly compatible with each other,
The friction coefficient of the magnetic layer surface is small, providing wear resistance, durability,
We have succeeded in obtaining a magnetic recording medium that satisfies all running stability requirements. One of the reasons why the above-mentioned lubricating film provides the good lubrication effect described above is that, due to its molecular structure, tetrafluoroethylene resin has extremely poor compatibility with molded metals and organic polymers. This seems to be similar to the phenomenon that produces an excellent lubricating effect.

[Structure and operation of the invention]

In this invention, the most preferable combination of at least two types of lubricants that are difficult to mix with each other is a combination of a liquid lubricant and a solid lubricant, where the former liquid lubricant usually becomes the "sea" and the latter By forming an island-like lubricating film in which the solid lubricant forms "islands," the excellent lubrication performance based on the above-mentioned reason can be better expressed.

The above-mentioned liquid lubricant is a lubricant that exhibits a liquid state at room temperature, and is selected from fluorine-based compounds, organic silicon-based compounds, and fatty acid esters in terms of affinity for the magnetic layer surface and its lubricating performance. is particularly preferred. On the other hand, the above-mentioned solid lubricant is a lubricant that exhibits a solid state (including semi-solid state) at room temperature, and is appropriately selected and used from among lubricants that have properties that are difficult to miscible with the above-mentioned liquid lubricant. However, from the viewpoint of lubrication performance, it is particularly preferable to select from among higher fatty acids, higher aliphatic esters, and fluorine compounds.

As a fluorine-based compound as a liquid lubricant, the following general formula (I), (ID; CF, CF3Y-CF20(-CF2CF, O+-+CF2O history CF
2 - ~100, m is 5 to 100, and n is 10 to 200).

In addition, in both of these formulas, X and Y at both ends of the molecule may be the same or different, but at least one of them may be a hydrophilic group or a monovalent group having a carbon-carbon double bond at the end of the molecule. When present, they are particularly useful in imparting affinity to the surface of the magnetic layer to form a continuous coating of "sea".

Examples of the above hydrophilic groups include hydroxyl group, carboxyl group,
Phosphate group [-0P(=O)(OH)zl, sulfonic acid group [O5("0)20H], incyanate group, metal salts of these groups, monovalent organic groups containing these groups or metal salts Here, as the metal salt, alkali metal salts such as Na, Ni, etc. are suitable, but alkaline earth metals, Fe
, Co, Ni, Cr, and other metal salts may also be used. In addition, examples of monovalent organic groups containing the above groups or metal salts include the following formulas (a) and (b); ÷A-)-M...(a)-
〇−0÷A+M・
・(b)1! (In the formula, A is an alkylene group having 40 or less carbon atoms, 2 carbon atoms
~4 alkylene oxide groups or polyalkylene oxide groups with a total carbon number of 80 or less of their adducts, M is a hydroxyl group, a carboxyl group, a phosphoric acid group, a sulfonic acid group, an incyanate group, or a metal salt of these groups) Examples include groups represented by the following, groups represented by the following formulas (c) to (e), and metal salts thereof.

-0(-R, O 坩H...(c) OR2R.

(R, is an alkylene group usually having 1 to 4 carbon atoms, R2+R
3, one of them is hydrogen and the other is a methyl group, or both are hydrogen, and q is an integer from 1 to usually 20). As a valence group, for example, the following formula (to); OR.

The most typical example is a (meth)acryloyloxy group represented by (R, is hydrogen or a methyl group) or an organic group containing this group via an alkylene group or the like.

The fluorine-based compound used as a liquid lubricant is not limited to the compounds represented by the above general formulas (I) and (D), and other known compounds having similar functions may also be used. good. For example, the general formula <ID
Those in which X or Y in nitrogen is an organic group that does not contain a hydrophilic group or a carbon-carbon double bond such as -C(=O)OR, (R5 is an alkyl group), or German Patent No. 2.839, 378
It is possible to arbitrarily use fluorine-based compounds such as those disclosed in the specification of the present invention.

In addition, examples of organic silicon compounds used as liquid lubricants include various polysiloxanes such as dimethylpolysiloxane and methylphenylpolysiloxane, and various known silicones having hydrophilic groups similar to those of the fluorine-based compounds introduced into the molecule. Compounds can be used. Furthermore, various known esters such as dioleyl maleate, trimethio-JL/furopane trisoccaate, and 2-ethylhexyl stearate are used as the fatty acid ester as a liquid lubricant.

On the other hand, fatty acids with 12 or more carbon atoms such as stearic acid are used as higher fatty acids that are prized as solid lubricants, and examples of higher aliphatic esters include monoalkyl esters of higher fatty acids with 16 or more carbon atoms and cellosolves. In addition to the above, phosphoric acid esters of higher aliphatic alcohols having the same number of carbon atoms as above can be used. In addition to general solid fluorine compounds, fluorine-based compounds include fluorine compounds that have hydrocarbon chains such as alkylene groups, alkylene oxide groups, or polyalkylene oxide groups in their molecules, and liquid compounds that have hydrocarbon chains in their molecules. A wide range of compounds can be used, including compounds with hydrophilic groups introduced therein similar to those used in lubricants.

In the present invention, at least one type of lubricant that is difficult to be mutually compatible is selected and used from among the liquid lubricants and solid lubricants described above. When selecting two or more types of liquid lubricants, these lubricants may be compatible or difficult to be compatible with each other. The same applies to the case where two or more types of solid lubricants are selected from among solid lubricants. In short, it is sufficient that at least the liquid lubricant and the solid lubricant are incompatible with each other. Here, mutually incompatible lubricants include lubricants that are not compatible with each other at all, as well as lubricants that are slightly compatible with each other but exhibit poor compatibility as a whole and exhibit a microphase separation phenomenon. The meaning also includes.

In the above combination of liquid lubricant and solid lubricant, the proportion of both used is as follows:
The liquid lubricant that should form an "island" should account for 5 to 99.9% by weight of the total, preferably 20 to 99.5% by weight, and the solid lubricant that should form an "island" account for 95 to 0.1% by weight of the total. , preferably 80-0
．． Preferably, it is in the range of 5% by weight.

In the magnetic recording medium of the present invention, the magnetic layer formed on the nonmagnetic support may be either a thin film of a ferromagnetic metal or metal oxide alone, or a coating film containing magnetic powder and a binder. It's okay. However, the effect of applying the present invention is particularly remarkable when the magnetic layer is made of the former magnetic thin film.

As the ferromagnetic metals and metal oxides constituting the former magnetic thin film, any conventionally known ferromagnetic metals and metal oxides can be used. Examples include alloys containing metals or nonmetallic elements, and oxides thereof.

To form a magnetic layer consisting of such a magnetic thin film, it may be carried out according to a conventional method, such as vacuum deposition, ion plating, It may be deposited by appropriate means such as sputtering or plating. The thickness of such a magnetic thin film is preferably about o, oos to 0.5P.

In addition, in a magnetic layer made of such a magnetic thin film,
Various coating layers may be formed for the purpose of surface protection. As such a protective coating layer,
For example, an oxide layer formed by forcibly oxidizing the surface of the magnetic layer, a layer made of a highly hard metal such as Ti or Bi or an oxide thereof, an inorganic material formed by vacuum evaporation, sputtering, plasma polymerization, etc. Examples include a thin film layer made of an organic substance. Moreover, these surface protective coating layers may be a composite layer of two or more types other than the above-mentioned individual layers.

On the other hand, when the magnetic layer is composed of a magnetic coating film, the magnetic powder includes γ-Fe, O, Fe50, intermediate oxides thereof,
Co-containing 7-Fe2O3, CO-containing Fe,, O,, Cr
Oxide magnetic powder such as O2, Ba, Sr, Pb ferrite, Fe.

Examples include metal magnetic powders such as Co, Ni, alloys thereof, and alloys containing these and other metals or small amounts of nonmetallic elements. Examples of binders include vinyl chloride-vinyl acetate copolymers, cellulose resins, polyurethanes, polyester resins, polyvinyl butyral, epoxy resins, polyols, and polyincyanate compounds as crosslinking agents.
Any conventionally known material can be used.

In order to form a magnetic layer consisting of such a magnetic coating film, it may be carried out in the same manner as conventional methods, for example, by preparing a magnetic coating material containing the above-mentioned magnetic powder and binder, and various additives as necessary. This may be coated on a non-magnetic support such as a polyester film and dried. Note that the thickness of such a magnetic layer is preferably about 0.1 to 20P. Further, examples of the various additives used as necessary include abrasives, dispersants, antistatic agents, and the like.

In the present invention, means for forming a sea-island-shaped lubricating film on the surface of the magnetic layer using at least two types of lubricants consisting of the liquid lubricant and the solid lubricant, which are difficult to dissolve in each other, is as follows. , various methods can be adopted, such as the method described above.

That is, the liquid lubricant and the solid lubricant are mixed in an appropriate solvent, for example, the liquid lubricant is a fluorine compound or an organic silicon compound represented by (I) or (ID), and the solid lubricant is a fluorine compound or the like. In some cases, it is dissolved in a fluorine-based solvent, a ketone-based solvent, an ester-based solvent, or a mixed solvent thereof, and this solution is applied or sprayed onto the surface of the magnetic layer, or conversely, the magnetic layer is immersed in the above solution. By adhering it and then drying it, the desired sea-island-shaped lubricating film is formed on the surface of the magnetic layer.

As another method, the magnetic layer is placed in a reduced pressure atmosphere, and the liquid lubricant and the solid lubricant are brought into contact with the surface of the magnetic layer in a gaseous state, thereby forming a sea-island shape on the surface. A lubricating film can be formed.

Furthermore, as another method, when the magnetic recording medium is a magnetic tape or the like, a back coat layer is formed on the surface, that is, the back surface, of the non-magnetic support opposite to the magnetic layer, and the above-mentioned liquid lubrication layer is formed in this back foot layer. The lubricant and the solid lubricant may be contained together, or the back coat layer itself may be formed from both of the above lubricants. Next, by stacking the magnetic recording media produced in this way (or winding the magnetic tape) so that the magnetic layer and the back coat layer come into contact with each other, the lubricant is transferred from the back coat layer to the magnetic layer. A sea-island-shaped lubricating film is formed by transfer adhesion.

Furthermore, in the case where the magnetic recording medium is a magnetic disk and this is loaded into a jacket to make a floppy disk, a liner made of nonwoven fabric or the like provided on the inner surface of the jacket is impregnated with the above-mentioned lubricants or their solutions. By allowing the liner to transfer and adhere to the surface of the magnetic layer in contact with the liner, the desired sea-island-shaped lubricating film can be formed.

The amount of adhesion of the sea-island-shaped lubricating film formed by these various methods is generally 0.5 to 0.5 to the surface of the magnetic layer.
Approximately 200~/m'' is appropriate. Too much (too much adhesion may cause interlayer adhesion, impairing running stability, etc., and may also result in good results in terms of electromagnetic conversion characteristics due to a decrease in surface texture). do not have.

A simpler method for forming a sea-island-shaped lubricating film according to the present invention is when the magnetic layer is a magnetic coating formed by applying and drying a magnetic paint, in which both of the above-mentioned lubricants are added to the magnetic paint. There is a method of containing both of the above lubricants inside the magnetic layer by blending them. That is, in this method, both of the above-mentioned lubricants contained inside the magnetic layer gradually leak out to the surface of the magnetic layer, and this leaching forms a sea-island-shaped lubricating film similar to that described above. .

The amount of both lubricants used in this method is 10
The amount is usually 0.2 to 20 parts by weight relative to 0 parts by weight.

In each of the above methods, whether or not a sea-island-like lubricating film is formed on the surface of the magnetic layer can be easily confirmed by microscopic observation.
It is also extremely easy to distinguish it from a lubricating film that corresponds to a lubrication film.

By the way, the above explanation is based on the fact that the liquid lubricant is the "sea".
Regarding the island-like lubricant coating where the solid lubricant forms "islands", if the solid lubricant has a stronger affinity for the magnetic layer surface than the liquid lubricant, then the solid lubricant forms "sea islands". ”, and it is also possible to form an island-like lubricating film in which the liquid lubricant forms “islands”. In this case, the amounts of both lubricants used and the method of forming the film are the same as described above.

Further, in the present invention, it is possible, depending on the case, that the at least two kinds of lubricants that are difficult to be mutually compatible may be composed of only liquid lubricants or only solid lubricants. In other words, even in such an embodiment, if the selected lubricants are difficult to miscible with each other and one has a significantly better affinity for the magnetic layer surface than the other, the above-mentioned microphase Due to the separation phenomenon, it is also essentially possible to form a lubricating coating in the form of sea islands.

[Effects of the Invention] As described above, in this invention, at least two kinds of lubricants that are hardly compatible with each other are used to form an island-shaped lubricating film on the surface of the magnetic layer, thereby achieving low friction. It is possible to exhibit an excellent lubrication effect with a coefficient of It is possible to provide a very high-performance magnetic recording medium that exhibits wear resistance, durability, and running stability, and also exhibits good electromagnetic conversion characteristics.

[Example] Hereinafter, this invention will be specifically explained based on examples.

In addition, in the following, parts mean parts by weight.

Example 1 A non-magnetic support made of a polyester film with a thickness of 1)/'' was surface treated (Ar gas) according to a conventional method.

After performing bombardment treatment), this was loaded into a vacuum evaporation apparatus, and cobalt was vacuum evaporated on the surface of the support under a residual gas pressure of 5 x 10 Torr of oxygen to a thickness of o,
A magnetic layer consisting of a ferromagnetic metal thin film of t pn was formed.

Next, on the surface of this magnetic layer, 7 parts of a fluorine-based compound (liquid lubricant) in which Y is a fluorine atom, ) was dissolved in 190 parts of trichlorotrifluoroethane as a solvent, and a lubricant solution was applied so that the non-volatile content was 50 my/lri, and dried to form a sea-island-shaped lubricating film. Thereafter, the magnetic tape according to the present invention was cut to a predetermined width. This invention was carried out in the same manner as in Example 1, except that a solution in which 7 parts of the compound (liquid lubricant) and 3 parts of dodecyl palmitate (solid lubricant) were dissolved in 190 parts of trichlorotrifluoroethane as a solvent was used. A magnetic tape was produced.

Example 3 As a lubricant solution, X and Y in the general formula (1)
is -C2I (, OH, m is 60, n is 120 fluorine-based compound (liquid lubricant) 7 parts and perfluoroalkyl ethanol (solid lubricant) 3 parts are added to 190 parts of trichlorotrifluoroethane as a solvent. A magnetic tape according to the present invention was produced in the same manner as in Example 1 except that the dissolved solution was used.

Example 4 As a lubricant solution, the general formula (in ID, X is -C
Ht CH20-P (=OXOH)2, Y is a fluorine atom, m is 60. 7 parts of a fluorine-based compound (liquid lubricant) with n of 120 and 3 parts of perfluorooctanoic acid (solid lubricant) were mixed with 190 parts of trichlorotrifluoroethane as a solvent.
A magnetic tape according to the present invention was produced in the same manner as in Example 1, except that a solution containing 100% of the 100% acetate was used.

Example 5 As a lubricant solution, 7 parts of a fluorine-based compound (liquid lubricant) having the general formula ([0, where X and Y are incyanate groups, m is 30, and n is 60] and octadecyl stearate (solid lubricant) were used. ) was dissolved in 190 parts of trichlorotrifluoroethane as a solvent.A magnetic tape according to the present invention was produced in the same manner as in Example 1, except that a solution of 3 parts of 3 parts of trichlorotrifluoroethane was used as a solvent.

Example 6 As a lubricant solution, 7 parts of a fluorine-based compound (liquid lubricant) in which X and Y are fluorine atoms, m is 30, and n is 60 in the general formula, and is represented by the following formula: % formula % 3 parts of fluorine compound (solid lubricant) and
A magnetic tape according to the present invention was produced in the same manner as in Example 1, except that a solution dissolved in 190 parts of trichlorotrifluoroethane was used as the solvent.

Example 7 As a lubricant solution, 6 parts of dimethylpolysiloxane (liquid lubricant) and 4 parts of butyl cellosolve stearate (solid lubricant) were mixed with 190 parts of methyl ethyl ketone as a solvent.
A magnetic tape according to the present invention was produced in the same manner as in Example 1, except that a solution containing 100% of the 100% acetate was used.

Example 8 The same procedure was carried out except that a solution in which 6 parts of methylphenylpolysiloxane (liquid lubricant) and 4 parts of stearic acid (solid lubricant) were dissolved in 190 parts of methyl ethyl ketone as a solvent was used as the lubricant solution. A magnetic tape according to the present invention was produced in the same manner as in Example 1.

Example 9 As a lubricant solution, 6 parts of trimethylolpropane trisocaate (liquid lubricant) and 4 parts of a fluorine-based compound (solid lubricant) represented by the following formula;
A magnetic tape according to the present invention was produced in the same manner as in Example 1, except that a solution dissolved in 190 parts of methyl ethyl ketone was used as the solvent.

Example 10 2-ethylhexyl stearate (2-ethylhexyl stearate) as lubricant solution
6 parts of liquid lubricant) and 2 parts of CIOF. (C)I2)20
A magnetic tape according to the present invention was produced in the same manner as in Example 1, except that a solution in which 4 parts of a fluorine-based compound (solid lubricant) represented by H was dissolved in 190 parts of methyl ethyl ketone was used as a solvent.

Example 1) As a lubricant solution, 5 parts of dioleyl malate (liquid film agent) and 5 parts of phosphoric acid ester of stearyl alcohol (solid lubricant) were used, and 1 part of methyl ethyl ketone was used as a solvent.
A magnetic tape according to the present invention was produced in the same manner as in Example 1, except that a solution containing 90 parts of the magnetic tape was used.

Example 12 On the back side of a non-magnetic support on which a magnetic layer was formed in the same manner as in Example 1, in the general formula (I), Y was a fluorine atom,
is a carboxyl group, l is 20, 3.5 parts of a fluorine-based compound (liquid lubricant), 3.5 parts of perfluorophosphate ester (solid lubricant), and a hydroxyl group-containing vinyl chloride-vinyl acetate copolymer ( Product name Vinilite vA manufactured by UCC in the United States
GH) 50 parts, ZnO powder (average particle size 0.2μ) 75
1 part, 650 parts of methyl ethyl ketone, and 3 parts of n-hebutane.
A back coat paint consisting of 0.00 parts was applied so that the thickness after drying was 21)M, and dried to form a back coat layer. Thereafter, the lubricant in the back coat layer is transferred and adhered to the surface of the magnetic layer by cutting it into a predetermined width and winding it, thereby forming a sea-island-shaped lubricating film on this surface. It was made into magnetic tape.

Example 13 Fe powder (average major axis diameter Q, 37 s, average axial ratio 10, specific surface area 50 m"/y by nitrogen adsorption method) 78 parts, car, bomb black (average particle diameter 30 mμ) 5 parts, nitrocellulose (Asahi Kasei) 10 parts of polyurethane elastomer, 100 parts of methyl ethyl ketone and n-
A magnetic paint consisting of 50 parts of hebutane was prepared, and this paint was coated on a non-magnetic support made of a polyester film with a thickness of 12 μm to a dry thickness of 4 μm, and dried to form a magnetic layer. .

Next, on the surface of this magnetic layer, 7 parts of a fluorine-based compound (liquid lubricant) in which X and Y are -C(0)OCH3, m is 60, and n is 120 in the general formula (II), and myristic acid ( A lubricant solution prepared by dissolving 7 parts of solid lubricant) in 186 parts of trichlorotrifluoroethane as a solvent was applied so that the nonvolatile content was 701 nl/lri, and dried to form a sea-island-shaped lubricating film. Thereafter, it was cut into a predetermined width to produce a magnetic tape according to the present invention.

Comparative Example 1 A magnetic tape was produced in the same manner as in Example 1, except that a solution prepared by dissolving 10 parts of squalane in 190 parts of methyl ethyl ketone as a solvent was used as the lubricant solution.

Comparative Example 2 A magnetic tape was produced in the same manner as in Example 1, except that a solution prepared by dissolving 10 parts of liquid paraffin in 190 parts of methyl ethyl ketone as a solvent was used as the lubricant solution.

Comparative Example 3 A lubricant solution was prepared by dissolving 10 parts of a fluorine compound (liquid lubricant) in the general formula CI) in which X and Y are fluorine atoms and l is 30 in 190 parts of trichlorotrifluoroethane as a solvent. A magnetic tape was produced in the same manner as in Example 1, except that .

Comparative Example 4 A magnetic tape was prepared in the same manner as in Example 1, except that the lubricant solution was a solution in which 10 parts of a fluorine compound (solid lubricant) represented by C1oF21SO3 was dissolved in 190 parts of acetone as a solvent. Created.

Comparative Example 5 A magnetic tape was produced in the same manner as in Example 12, except that 8 parts of squalane was used as the lubricant.

Comparative Example 6 A magnetic tape was produced in the same manner as in Example 13, except that a solution prepared by dissolving 14 parts of liquid paraffin in 186 parts of methyl ethyl ketone as a solvent was used as the lubricant solution.

Regarding each of the magnetic tapes obtained in the above Examples and Comparative Examples, the coefficient of friction, durability, and jitter of the magnetic layer were examined by the following methods, and the results shown in the table below were obtained.

<Friction coefficient> The sample tape was wound around a cylindrical pin with a surface roughness of 0.2 S and an outer diameter of 41 M1) at a winding angle of 150°, and the tape was fed at a tape feed rate of 1.4 c++/sec with a load of 21 y applied.
Repeat this 100 times for the same part of the tape,
The friction coefficient for the 00th time was determined.

Jitter> Using a standard video tape recorder, the tape was run at a speed of 1°4cm/sec with a tension of 6y applied to it, and the jitter value was calculated when color bar symbols were recorded and played back over a tape length of 5m. Read with a jitter meter.

<Durability> Under the conditions of 25°C and 260% RH, the obtained magnetic tape was played by running at a head load of 5y1 and a running speed of 0.048 m/sec, and the number of runs until the output decreased by 3 dB from the initial output was determined. It was measured.

Next, for each of the magnetic tapes of the above examples and comparative examples, the relationship between the sliding speed and the coefficient of friction of the magnetic layer was investigated. The results are shown in Example 1 (curve-a in the figure) for Examples 1-13 as a representative example, and Comparative Example 1 (curve-b in the figure) for Comparative Examples 1-6 as a representative example. Examples 2 to 13 had almost the same results as Example 1, and Comparative Examples 2 to 6 had almost the same results as Comparative Example 1.

As is clear from the test results described below, the magnetic tape according to the present invention has a small coefficient of friction on the surface of the magnetic layer and no increase in the coefficient of friction with increasing sliding speed, and has very good durability. In addition, it can be seen that there is little deterioration of jitter due to the number of runs, and the running stability is good.

[Brief explanation of drawings]

The drawing is a characteristic diagram showing the relationship between the sliding speed and the friction coefficient of the magnetic layer for magnetic tapes of the present invention and for comparison.

Claims (8)

[Claims] (1) A magnetic recording medium characterized in that an island-shaped lubricating film made of at least two types of lubricants that are hardly compatible with each other is formed on the surface of a magnetic layer formed on a non-magnetic support. . (2) The magnetic recording medium according to claim (1), wherein the at least two types of lubricants that are hardly compatible with each other are a combination of a liquid lubricant and a solid lubricant. (3) The liquid lubricant is selected from fluorine compounds, organosilicon compounds, or fatty acid esters, and the solid lubricant is selected from higher fatty acids, higher aliphatic esters, or fluorine compounds. ) The magnetic recording medium described in item 2. (4) Fluorine compounds used as liquid lubricants have the following general formulas (I) and (II); ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) Y-CF_2O-(CF_2CF_2O)_m-( C.F.
_2O)_nCF_2-X...(II) (wherein, X, Y
is a fluorine atom, a hydrophilic group, or a monovalent group having a carbon-carbon double bond at the end of the molecule, l, m, and n are integers, and l is 10
100, m is 5 to 100, and n is 10 to 200). (5) The hydrophilic group constituting X and/or Y is a hydroxyl group,
Claim No. 4 selected from carboxyl groups, phosphoric acid groups, sulfonic acid groups, isocyanate groups, metal salts of these groups, and monovalent organic groups containing these groups or metal salts.
) The magnetic recording medium described in item 2. (6) Carbon-carbon at the end of the molecule constituting X and/or Y
A monovalent group having a carbon double bond is a (meth)acryloyloxy group represented by the following formula; ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (R_4 is hydrogen or methyl group) or an organic group containing this group. The magnetic recording medium according to claim (4), which is a base material. (7) The magnetic recording medium according to claim (3), wherein the fluorine-based compound as a solid lubricant has a hydrocarbon chain consisting of an alkylene group, an alkylene oxide group, or a polyalkylene oxide group in the molecule. (8) At least two types of lubricants that are hardly compatible with each other
The magnetic recording medium according to any one of claims (2) to (7), comprising 99.9% by weight of a liquid lubricant and 95 to 0.1% by weight of a solid lubricant.